Hydrolysis of the protein contained in the pig bone residue from ham production was performed using the commercial enzymatic preparation Neutrase (R). Enzymatic hydrolysis was carried out in a 2-litre bio-reactor at 55 degrees C and a pH of 7.0. The influence of the process variables on the degree of hydrolysis (DH), nitrogen recovery (NR) and the peptides molecular weight distribution was studied. The highest DH (12.4%) was obtained after 120 min hydrolysis with a 2.5% enzyme/substrate relation. The hydrolysis reaction mechanism is developed in two stages, as the nitrogen recovery does. The existence of a linear correlation between the degree of hydrolysis and the nitrogen recovery was proved. The commercial enzymatic preparation Neutrase (R) showed good efficiency in the hydrolysis and extraction of the protein present in the pig bone. (C) 2013 Elsevier Ltd. All rights reserved.